Hydraulic vehicle brake systems are known that take the form of power brake systems and include—in addition to a master brake cylinder which can be actuated by muscular force, to which wheel brakes are hydraulically linked, and which provides pressure and volume for the purpose of actuating wheel brakes—a further, electrically controllable device for providing pressure and volume, which triggers the wheel brakes in a “brake-by-wire” operating mode. In the event of failure of the electrically controllable device for providing pressure and volume, an actuation of the wheel brakes is effected solely by the muscular force of the driver of the vehicle.
From WO 2011/029812 A1 an electrohydraulic brake system is known having a master brake cylinder, which can be actuated by the brake pedal, a travel simulator and a pressure-supply device. In a “brake-by-wire” operating mode the wheel brakes are pressurized by the pressure-supply device. The master brake cylinder and hence the driver of the vehicle are isolated from the wheel brakes via closed isolating valves. In the case of an anti-lock feedback control in the “brake-by-wire” operating mode, the driver therefore receives no brake-pedal reaction.
It is an object of the present invention to propose a method and a brake system that make available, in particular with simple electronic means, a haptic information channel via which, in particular during a braking operation in a “brake-by-wire” operating mode, information can be communicated in electronically controlled form to the driver without the impression of a defect arising.
In accordance with the invention this object is achieved by a method and by a brake system as described herein.